When comparing SciTE vs TextWrangler, the Slant community recommends TextWrangler for most people. In the question“What are the best programming text editors for a Mac with a GUI?”TextWrangler is ranked 10th while SciTE is ranked 16th. The most important reason people chose TextWrangler is:

Pros

Pro

Powerful

Based on the Scintilla source code editor, SciTE has some advanced features like rectangular editing, simple regular expression search and replace, code folding, etc. It allows the user to launch a compiler or interpreter, and it can also interpret the error messages, jumping at the location they point to.

Lua scripting is key to SciTE's power and flexibility. The Lua scripting language can be used to perform complex text transformations. It's relatively simple syntax and its large user-base makes it a great choice for a scripting feature.

Pro

Flexible

It's property files allow for fine tweaks of its behavior, at a global or per language / project level. These textual settings might be confusing for those used to preference dialogs, but prove to be powerful, flexible, and fine grained.

Pro

Lightweight

With less than 2 MB of binary on Windows, SciTE starts instantly. Plus, if you don't need all the config, syntax files, blah, there's a 678k standalone .exe version. Nothing is going to beat that for lightweight and start-up times. Stick it in a folder that is already on your PATH.

Pro

Built-in shell

The console window can show the result of ran commands (like build current file, reporting warnings, and errors), but also accept interactive shell commands.

Pro

Portable

SciTE works on Windows and Linux, and it also has a commercial port on MacOS.

Pro

Powerful syntax highlighting for numerous languages

Lexers providing folding and syntax highlighting are based on code, not on regular expressions. They support context, nesting, special rules, etc.

Pro

Free (except on Mac) and open source

SciTE is written in C++, with lot of contributors, both to the core and to the numerous lexers.

Pro

GUI

Has a simple graphical user interface

Pro

Free

Free but capable alternative to BBEdit.

Pro

Built-in FTP/STFP browser

Edit remote files easily.

Pro

Fast to start up

It starts up fast because is not bloated. It has all the essentials of a text editor.

Pro

Robust

Cons

Con

Hard to config

The configuration is mainly a file-based config, which can be unintuitive and difficult to use for new users.

Con

Missing file browser

SciTE's greatest weakness is perhaps the file browser. It does not really have one, just a poor substitute which works a little bit like a terminal window with ls or dir commands to show the files in a directory.

Con

Customization

No extensions, Themes.

Con

No Longer Maintained

Bare Bones, the developers of TextWranger, recently ended maintenance and support for the product. Per the Bare Bones website (https://www.barebones.com/products/textwrangler/): "We have sunsetted TextWrangler, and we encourage anyone interested in TextWrangler to download and use BBEdit instead."

Con

Not Compatible with macOS High Sierra (10.13+)

Per the Bare Bones website (https://www.barebones.com/support/new-os.html): "TextWrangler is not compatible with High Sierra. We suggest that you use BBEdit as an alternative . . . ." Since Bare Bones officially sunsetted the product, it will unlikely be compatible with subsequent macOS release versions either.